In such a filter device, the precoat agent nozzle is arranged in the intake opening in order to reliably mix the precoat agent with the target gas flowing into the device casing through the intake opening.
In a conventional filter device as shown in FIG. 1 of Patent Document 1, a simple circular or rectangular opening acting as the intake opening is formed in a plate member forming the device casing, and the precoat agent nozzle is arranged in such an opening to be directed to the interior of the device casing (Prior Art 1).
In another conventional filter device shown in FIGS. 1 and 2 of Patent Document 2, the precoat agent nozzle is provided in the vicinity of the intake opening in the interior of the device casing (Prior Art 2).
On the other hand, an example of the painting booth for catching the paint mist contained in exhaust air discharged from a painting chamber by the filter is shown in FIGS. 1 and 15 of Patent Document 3.
In the painting booth as shown in FIG. 1 of Patent Document 3 (see FIG. 7 of the present application), an exhaust chamber 4 is provided under the painting chamber 2 for receiving the exhaust air EA from the painting chamber 2.
A pair of guide plates 20 is provided for partitioning the exhaust chamber 4 into an upper region and a lower region, and a central slit-like gap 21 is formed between tip end edges of the pair of guide plates 20.
The central slit-like gap 21 extends in a longitudinal direction of the booth (that is, a direction of transporting a target object in the painting chamber 2).
The lower region formed by partitioning the exhaust chamber 4 by the guide plates 20 acts as a filtering chamber including a plurality of filters arranged therein. The plurality of filters are arranged in the longitudinal direction of the booth.
The precoat agent nozzle 11 is provided in a back side surface of one of the guide plates 20 in the vicinity of the central slit-like gap 21 for ejecting the precoat agent P toward the exhaust air EA passing through the central slit-like gap 21 (Prior Art 3).
In the painting booth shown in FIG. 15 of Patent Document 3 (see FIG. 8 of the present application), vertical plates 22 surrounding the filters 8 together with the guide plates 20 are suspended from the end portions of the guide plates 20. A bottom slit-like gap 23 is formed between a lower edge of each vertical plate 22 and the bottom of the exhaust chamber 4. The bottom slit-like gap 23 also extends in the longitudinal direction of the booth.
The precoat agent nozzle 11 is provided in a back side surface of each vertical plate 22 in the vicinity of the bottom slit-like gap 23 for ejecting the precoat agent P toward the exhaust air EA passing through the bottom slit-like gap 23 (Prior Art 4).
More particularly, in those painting booths, the precoat agent P is ejected toward a high-speed flow of the exhaust air EA passing through the central slit-like gap 21 or bottom slit-like gap 23.
This allows the precoat agent P to mix with the exhaust air EA uniformly with agitation caused by the high-speed flow of the exhaust air EA, and then allows the exhaust air EA to pass through the filters 8.